Pedal-controlled rheostat for musical instruments.



M L SEVERY & G B SINCLAIR PEDAL CONTROLLED RHEOSTAT FOB, MUSICAL INSTRUMENTS. APPLICATION FILED AUG. 7, 1905. RENEWED OCT, 4, 19-13- 1 097,053, Patented May 19, 1914 WYZIwMeIL- fwening Mai/ML. Seq/ar y, G

6 061902.. Sinclcbim UNITED STATES PATENT OFFICE.

MELVINL. SEVERE, 01- ABLINGTON HEIGHTS, AND GEORGE B. SINCLAIR, OF

WINTHROP, IAS SACHUSETTS, ASSIGNOBS T0 CHOBALCELO uauuracrunmo commnr, A oonrom'rzon or MAINE.

nun-commoner annos'rar roa nosIcAL INSTRUMENTS.

' Application filed August 7, 1805, Serial No.

To all whom it may concern:

Be it known that we, MELVIN LJSEVERY, of Arlington Heights, in the county of Mid- .dlesex, State of Massachusetts, and Groxon B. SINCLAIR, of Winthrop, in the county of Suffolk, in said State, both citizens of the United States, have invented certain new and useful Improvements in Pedal-Con= trolled Rhcostatsfor Musical Instruments, of which the following is a full, clear, and exact description.

The object of this invention is the construction of means by which loud and soft effects can be produced simultaneously and equally upon all the notes sounded in amusical instrument wherein the strin s are vibrated by electrically .pulsated e ectromagnets.

In certain co-pending applications we have shown, described and c aimed features which are illustrated and described in the present application, but which are not herein claimed, and in other co-pending-applications we have broadly claimed the art of producing musical tones, which art is involved but is not claimed in the present application. All matters set forth and claimed in co-pending applications filed in our names, or in the name of either of us, and not specifically claimed herein, are expressly saved and reserved for one or another of such co-pending applications. Among these may be noted our joint applications Serial Nos. 273,199; 273,202; 379,714; 384,872; 537,257; 563,437; 753,014; and 754,475; and the sole applications of M. L. Severy, Serial Nos. 619,633 and 620,002.

Referring to the drawings forming part of this specification, and which give a. perspective view mainly in diagram of the embodiment of our invention, the reference numeral l designates the keys of the instrument, 10 the strings thereof, 20 the electromagnets for actuating said strings, 40 the current interrupting device by means of which the suitable electric pulsations are produced for said magnets, the source of electricity, 37 the pedal for operating the rheostat, and 80 the rheostat framework. Pivoted to said framework at 73 are arms 72 carrying a cross bar 71 to which are se- Specification of Letters Patent.

.cured as many brushes as there are elec- I trornagnets 20. Said bar and arms are counterbalanced by a suitable spring 75 attached to the arm-'pro1ongation44, and they are swung up and down by means of the horizontal bar 76 having its ends bent'vertically upward and pivoted to the. arms 72, the vertically descending connecting-rod 77 formed as a part of said bar, and'the pedal 37, to the rear end of which said rod is pivoted.

The framework 80 supports a surface of insulating material, preferably wood, curved cylindrically concentric with said pivots 73, and upon this curved board 81 are fixed a multiplicity of contact-blocks 88 of suitable conducting material as copper or brass, arran ed in rows extending both horizontally an vertically, but each contact insulated from every other one. The vertically extending rows are'equal in number to said'brushes, and are positioned to have each vertical row swept by the latter from top to bot-tom as the bar 71 is swung up and down as above described. v i

'Between the two horizontal frame-beams 83, 84, which are preferably composed of insulating material as .wood,- are fixed a number of rods of compressed graphite 85, or other poor conductor, the lower end of each of which is wired individually to a brush 41 of the current interrupting device 40, and also to the lowest one of the contact blocks 88 by wires 42, 43, in order that when the brushes 70 are depressed into touch with the lowest row of said blocks 88, the full strength of current will be transmitted to the magnets 20. The second row of contacts is wired to the same rheostat-rods 85, but a short distance up from their lower ends; each contact to a separate rod. Then the third row is wired an equal distance farther up, and so on until the topmost row is wired to the upper ends of said rods. Accordingly, as the pedal is depressed and the brushes raised higher and higher, a steadily increasing resistance is put into each circuit, and the electromagnets made to correspondingly reduce their vigor of action upon the strings. With our arrangement, a .pedal rheostat is thus provided Patented May 1-9, 1914. 273,203. 'I Benewcd October 4, 1913. Serial No. 793,481.

which will equally reduce the loudness of the strings no matter how many or how few are vibrated. at a time.

As shown in the left-hand section of the framework 80, the rheostat rods are not all the same in diameter, but become larger as the extreme left-hand end is reached. 'llhe same difference in size of said rods is made toward the right-hand end, inasmuch as the more slender the resistance-rod or pencil is made, the greater the reslstance given to the current for the same length of pencil-section. Consequently, for the same shift of the brush-bar 71, the greater will be the resistance thrown into the circuits to the middle notes of the piano than either the lowest bass notes or the high treble notes. The reason for this appears to be that, under practical conditions, the magnets near the middle of the scale are more effective than those at the ends, and so a greater resistance is needed to produce a pianissimo effect in the middle. Of course there are other methods of varying the resistances for the same degrees of depression of the pedal, as by keeping the rods or pencils of the same diameter and lengthening them, but the arrangement shown possesses certain advantages of simplicity in mounting and Wiring.

The current-interrupting members 40 must, we have found, be rotated with practically perfect synchronism; in fact, the synchronism we actually attain is so perfect as not to exhibit the slightest beat to the ear of the trained tuner; means for accomplishing this result with practically absolute precision being disclosed in our companion applications Serial Nos. 7 54,47 5, 384,87 2 and 620,002. The reason for this is evident when it is realized that, as we have found, the difference between absolute synehronism and a one-thousandth of a degree off is enough to produce so wide a difference in the volume of tone 'as to prevent any pedal action from being used with any proper effect in the presence of such volumefiuctuations. None of the so-called governing devices shown by others are a one-hundredth part accurate enough for constancy of tone, being too crude even to get any considerable tone at all, let alone maintaining it with uniform loudness. It is hence quite obvious that an indispensable requisite to musical expression in such tones is that they shall be constant for equal amounts of current delivered to their magnets, and this condition will be absolutely defeated if the current pulsation mechanism is not kept practically in perfect synchronism.

What we claim as our invention and for which we desire Letters Patent is as follows, to wit l. The combination with sonorous bodies, electromagnets for their actuation, and

means including circuits for delivering electric pulsations to said electromagncts, of means for varying the resistances of all the circuits to said electro-magnets simultaneously, such resistance-varying means comprising a series of cylindrical extended resistances insulated from each other; a multiplicity of insulated contacts arranged in horizontal rows; connections bet-ween designated contacts in one row and designated contacts in other rows; brushes equal in number to the contacts in each horizontal row; and means for moving said brushes from row to row.

2. The combination with sonorous bodies, electromagnets for their actuation, and means for delivering electric pulsations to said electromagnets, of means for varying the resistances in all the circuits to said electromagnets simultaneously, such resistance-varying means comprising a series of elongated resistances insulated from each other; a multiplicity of insulated tesscllated contacts; connections between the contacts in each transverse row and different points of one of said resistances; brushes equal in number to said transverse rows; and means for moving all said brushes simultaneously along said transverse rows, each brush and one end of the corresponding resistance being in the circuit of one of said electromagnets.

3. The combination with sonorous bodies, electromagnets for their actuation, and means for delivering electric pulsations to said electromagnets, of means for varying the resistances in all the circuits to said electromagnets simultaneously, such resistance-varying means comprising a series of elongated resistances insulated from each other; a multiplicity of insulated tessellated contacts located on a cylindrical surface; connections between the contacts of each transverse row and different parts of one of said resistances; brushes equal in number to said transverse rows; a bar carrying said brushes; and a pedal for moving said bar and contacts relative to each other to cause said brushes to engage different contacts in the transverse rows, each brush and 1 5 one end of the corresponding resistance being in the circuit of one set of electromagnets.

l. The combination with sonorous bodies,

a source of current, circuits, electromagnets 2 controlling said sonorous bodies, and means for delivering electric pulsations to said electromagnets. of means for varying the resistances in all the circuits to said electromagnets simultaneously, such resistancevarying means comprising a series of parallel graphite pencils; supporting means for the latter; a multiplicity of insulated tessellated contacts; connections between the contacts in each transverse row and difier- 1 g ent arts of one of said pencils; brushes invention, we have hereunto set our hands eqlglai in nufmber to saidntrandsvgrsehrows; this 21st day of July, 1905. 10 an means or movm a $111 rus es Slmultaneously along sgid transverse rows, 5 each brush and one end of the eorrespondin pencil being in the circuit of one of sai Witnesses: electromagnets. FRED G. TILTON, Intestimony that we claim the foregoing A. B. UPHAM. 

